ACLS Algorithm Overview
Advanced Cardiovascular Life Support (ACLS) algorithms form the backbone of paramedic cardiac care. The NREMT Paramedic exam tests your ability to apply these algorithms to clinical scenarios, make drug and intervention decisions, and recognize when to deviate from standard protocols.
Cardiac Arrest Algorithm
Shockable Rhythms: VF and Pulseless VT
Begin high-quality CPR immediately. Attach defibrillator and analyze rhythm. If VF/pVT is identified:
- Defibrillate at maximum joules (biphasic: manufacturer recommendation, typically 120-200J; monophasic: 360J)
- Resume CPR immediately for 2 minutes
- After second shock: Epinephrine 1 mg IV/IO every 3-5 minutes
- After third shock: Amiodarone 300 mg IV/IO bolus (second dose 150 mg) OR Lidocaine 1-1.5 mg/kg IV (subsequent doses 0.5-0.75 mg/kg)
- Continue cycle: CPR, analyze, shock if indicated, drugs
Non-Shockable Rhythms: PEA and Asystole
- Begin high-quality CPR
- Epinephrine 1 mg IV/IO as soon as IV/IO access is established, then every 3-5 minutes
- Identify and treat reversible causes (H's and T's)
- Do NOT defibrillate asystole or PEA
The H's and T's
Reversible causes of cardiac arrest that must be identified and treated:
- H's: Hypovolemia, Hypoxia, Hydrogen ion (acidosis), Hypo/Hyperkalemia, Hypothermia
- T's: Tension pneumothorax, Tamponade (cardiac), Toxins, Thrombosis (pulmonary), Thrombosis (coronary)
Bradycardia Algorithm
For symptomatic bradycardia (HR less than 50 with hypotension, altered mental status, chest pain, or heart failure):
- Atropine 1 mg IV every 3-5 minutes (max 3 mg)
- If atropine is ineffective: Transcutaneous pacing (set rate 60-80, increase milliamps until capture)
- Alternative: Dopamine infusion 5-20 mcg/kg/min OR Epinephrine infusion 2-10 mcg/min
Note: Atropine is NOT effective for second-degree Type II or third-degree (complete) heart block. Go directly to pacing for these rhythms.
Tachycardia Algorithm
Unstable Tachycardia (with pulse)
If the patient is unstable (hypotension, altered consciousness, chest pain, acute heart failure), perform immediate synchronized cardioversion regardless of rhythm type. Start at 50-100J for narrow complex, 100J for wide complex.
Stable Narrow Complex Tachycardia
If regular (likely SVT):
- Vagal maneuvers first (modified Valsalva, carotid massage)
- Adenosine 6 mg rapid IV push with flush. If no response, 12 mg rapid IV push (may repeat once)
If irregular (likely AFib/flutter): Rate control with diltiazem 0.25 mg/kg IV over 2 minutes or beta-blocker per protocol
Stable Wide Complex Tachycardia
If regular and monomorphic: Amiodarone 150 mg IV over 10 minutes OR Procainamide 20-50 mg/min IV
If polymorphic (possible torsades): Magnesium sulfate 1-2 g IV over 5-20 minutes. If unstable, defibrillate (not synchronized cardioversion).
Post-ROSC Care
After return of spontaneous circulation:
- Optimize ventilation: SpO2 94-99%, ETCO2 35-45 mmHg. Avoid hyperventilation
- Maintain systolic BP above 90 mmHg (fluid bolus, vasopressors as needed)
- Obtain 12-lead ECG to assess for STEMI
- Targeted temperature management if patient remains comatose
- Transport to cardiac catheterization capable facility